(F-18) fluorodeoxyglucose positron emission tomography as a predictor of pathologic grade and other prognostic variables in bone and soft tissue sarcoma

Positron emission tomography (PET) can be used to measure tumor metabolism in sarcomas by measuring the standard uptake value (SUV) of (F-18) fluorode oxyglucose (FDG). FDG-PET SUV has been shown to correlate with histological grade. We compared FDG-PET SW in 89 bone and soft tissue sarcomas with his topathological features, including tumor grade, as well as with markers of cell proliferation and cell cycle regulatory gene expression that may be pr ognostically or therapeutically important. All patients had undergone PET b efore biopsy. Features evaluated included grade (National Cancer Institute for soft tissue or Mayo Clinic for bone), cellularity, and the number of mi toses per 10 400 x fields. Deparaffinized, formalin-fixed sections were imm unostained with antibodies to Ki-67 (MIB-1), p53 (DO7), p21(WAF1) (EA10), a nd mdm-2 (1B10). For Ki-67, results were estimated as a percentage of posit ive cells, For p53 and mdm-2, only cases with >20% positive cells were cons idered to be overexpressing these proteins. For p21(WAF1), only cases with <10% positive cells were considered to have lost normal p21(WAF1) expressio n. Tumor S-phase percentage and ploidy were determined by flow cytometry, F DG-PET SUV was associated with histopathological grade, cellularity, mitoti c activity, MIB labeling index, and p53 overexpression. No association was seen with p21(WAF1), mdm-2, S-phase fraction, or ploidy. Tumor metabolism d ata acquired by FDG-PET may help ensure accurate grading and prognosticatio n in sarcoma by guiding biopsy toward the most biologically significant reg ions of large masses. Further follow-up will be necessary to determine whet her FDG-PET provides independent prognostic information.